Yes, there is unfortunately an issue with our cookie banner, in that it is only informational, and does not actually allow you to actively reject use of cookies.
For all intents and purposes, we are talking about the NodeBB session cookie. We do not save any other kind of cookie.
The moment you land on the site, actually, you get a session cookie, whether or not you accept the cookie banner is irrelevant. We really ought to change this so it actually grants a choice, but it is not a light undertaking, since we would have to rewrite parts of the software that handle session data (if consent is not given).